Lithium metal anode and lithium secondary battery comprising same

Abstract

A lithium metal anode and a lithium secondary battery including the same are provided. The lithium metal anode comprises a lithium metal layer arranged on a current collector and a protective layer arranged on the lithium metal layer, the protective layer comprises a polymer binder and lithium conductive particles, and the polymer binder is non-polar. The polymeric binder may be fluorine (F) free. A lithium electrodeposited layer of the lithium metal layer may have a thickness of about 15 microns or greater. The weight ratio of the lithium conductive particles to the polymer binder (lithium conductive particles (wt%) / polymer binder (wt%)) may be about 2.0 to 10.0.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2024-0111028, filed on August 20, 2024, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a lithium secondary battery, and more specifically, to a lithium metal anode and a lithium secondary battery comprising the lithium metal anode. Background Technology

[0004] A battery is an energy storage source that can convert chemical energy into electrical energy or electrical energy into chemical energy. Batteries can be divided into non-reusable primary batteries and reusable secondary batteries. Compared with primary batteries that are discarded after one use, secondary batteries have a more environmentally friendly advantage because they can be reused.

[0005] In recent years, with increasing attention to environmental issues, the demand for hybrid electric vehicles (HEVs) and electric vehicles (EVs) with low or no air pollution has also been increasing. In particular, EVs, which are vehicles without internal combustion engines, foreshadow the future direction of the world.

[0006] Lithium-ion batteries are used as the energy source for many electric vehicles (EVs). A lithium-ion battery mainly consists of a positive electrode, a negative electrode, an electrolyte, and a separator. In the positive and negative electrodes, lithium ions repeatedly intercalate and deintercalate to generate energy. The electrolyte serves as a channel for lithium ion migration, and the separator prevents contact between the positive and negative electrodes, thus avoiding short circuits.

[0007] Specifically, the positive electrode is closely related to the battery's capacity, while the negative electrode is closely related to its performance, such as fast charging and discharging. The electrolyte consists of a solvent, additives, and lithium salt. The solvent acts as a migration channel, helping lithium ions migrate between the positive and negative electrodes. For the battery to perform well, lithium ions must transfer rapidly between the positive and negative electrodes.

[0008] Incidentally, lithium metal possesses an excellent theoretical capacity (3,860 mAh / g) and a very low standard reduction potential (standard hydrogen electrode, SHE) (-3.045 V), enabling batteries to achieve high capacity and high energy density. Therefore, various studies have been conducted on lithium metal anodes, using lithium metal as the negative electrode active material in lithium-ion secondary batteries.

[0009] However, due to the low reduction potential and large volume change of the lithium metal anode, the solid electrolyte interface (SEI) acting as the lithium electrolyte membrane is difficult to form, leading to continuous and unstable electrolyte decomposition. Furthermore, the following problems exist: the electrolyte may be depleted at the negative electrode, resulting in a shortened battery life, or the reaction between the lithium metal anode and the electrolyte may deplete the negative electrode, further shortening battery life.

[0010] To address these challenges, various studies are underway attempting to create a protective layer on the surface of lithium metal anodes that reacts with the electrolyte to prevent electrolyte decomposition.

[0011] However, the traditional protective layer applied to the surface of the lithium metal anode has issues with its reactivity with lithium. Furthermore, when lithium batteries are deposited on the lithium metal anode, the protective layer can be torn or damaged due to inhomogeneity, allowing electrolyte to flow through the protective layer into the lithium metal anode. This increases the resistance of the negative electrode and reduces the battery's charge / discharge efficiency. Summary of the Invention

[0012] The technical problem to be solved by some embodiments of the present invention is to provide a lithium metal anode that, by minimizing reactivity with lithium, prevents electrolyte from flowing into the lithium metal layer even when lithium is non-uniformly electrodeposited inside or on the surface of the lithium metal layer, thereby giving the lithium metal anode improved lifetime characteristics.

[0013] Another technical problem to be solved by some embodiments of the present invention is to provide a lithium secondary battery including a lithium metal anode having the above-mentioned advantages.

[0014] Another technical problem to be solved by some embodiments of the present invention is to provide a method for manufacturing a lithium metal anode having the above-mentioned advantages.

[0015] According to some embodiments of the present invention, a lithium metal anode includes a lithium metal layer disposed on a current collector and a protective layer disposed on the lithium metal layer, wherein the protective layer includes a polymer binder and lithium conductive particles, and the polymer binder is non-polar. In some embodiments, the weight ratio of lithium conductive particles to polymer binder (lithium conductive particles (wt%) / polymer binder (wt%)) can be from about 2.0 to 10.0.

[0016] In some embodiments, the thickness of the protective layer can be from 10 micrometers to 20 micrometers. In some embodiments, the average particle size (D50) of the lithium conductive particles can be from 100 nanometers to 850 nanometers. In some embodiments, the polymer binder can be a highly elastic polymer.

[0017] In some embodiments, the polymeric adhesive may be fluorine-free (F). In some embodiments, the polymeric adhesive may include at least one of styrene-based polymers, block copolymers, polyolefin-based polymers, polyurethane-based polymers, and silica-based polymers.

[0018] In some embodiments, the lithium conductive particles may include at least one of lithium-based oxides, nitrides, sulfides, fluorides, phosphides, and solid electrolyte materials. In some embodiments, the protective layer may include a solvent, which may contain 30% to 50% solids content per 100% by weight of the protective layer.

[0019] In some embodiments, the solvent may include at least one of benzene, toluene, xylene, and alkane-based materials. In some embodiments, the protective layer may further include a dispersant, and the content of the dispersant may be 3% by weight or less per 100% of the protective layer.

[0020] In some embodiments, the lithium conductive particles may include a doped material, and the doped material may be an Nb-based material. In some embodiments, the fill density of the polymer binder and the lithium conductive particles in the protective layer may be 30% to 50% by weight of the solid content, based on 100% by weight of the protective layer.

[0021] In some embodiments, the lithium conductive particles may include fine particles and coarse particles with an average particle size larger than the fine particles, and the weight ratio of the fine particles to the coarse particles (fine particles (weight%): coarse particles (weight%)) may be from 0.5:9.5 to 3.0:7.0.

[0022] In some embodiments, the lithium metal anode may further include a lithium-ion battery deposited layer in the lithium metal layer, the thickness of which may be 5 micrometers to 15 micrometers. In some embodiments, the lithium metal layer may also include an initial lithium layer and a lithium-ion battery deposited layer disposed on the initial lithium layer, the average thickness ratio of the initial lithium layer to the lithium-ion battery deposited layer (initial lithium layer: lithium-ion battery deposited layer) may be 5:5 to 20:20.

[0023] According to some embodiments of the present invention, a lithium secondary battery may include the lithium metal anode described above.

[0024] According to some embodiments of the present invention, the lithium metal anode includes a protective layer disposed on a lithium metal layer, the protective layer comprising a nonpolar polymer binder and lithium conductive particles, thereby minimizing reactivity with lithium and preventing electrolyte from flowing into the lithium metal layer even when lithium is non-uniformly electrodeposited inside or on the surface of the lithium metal layer, thereby giving the negative electrode improved lifetime characteristics.

[0025] According to some embodiments of the present invention, a lithium secondary battery includes a lithium metal anode having the advantages described above, thereby providing the battery with improved lifespan characteristics.

[0026] As discussed, the method and system appropriately include the use of a controller or processor.

[0027] In some implementations, vehicles are provided that include devices as disclosed herein. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a lithium metal anode according to some embodiments of the present invention;

[0029] Figure 2 This is a plan view of a lithium metal anode according to an embodiment of the present invention;

[0030] Figure 3 A plan view of the lithium metal anode according to the comparative embodiment;

[0031] Figure 4 This is a cross-sectional view of a lithium metal anode according to an embodiment of the present invention;

[0032] Figure 5 This is a cross-sectional view of the lithium metal anode according to the comparative embodiment;

[0033] Figure 6 A graph illustrating the lifetime characteristics of a lithium metal anode according to an embodiment of the present invention is shown.

[0034] Figure 7 A graph illustrating the lifetime characteristics of the lithium metal anode according to a comparative embodiment;

[0035] Figure 8 A graph showing the charging voltage vs. capacity according to embodiments and comparative embodiments of the present invention is shown;

[0036] Figure 9 A plan view of the surface of the lithium metal anode after full charging is shown according to embodiments and comparative embodiments of the present invention;

[0037] Figure 10 A graph showing capacity vs. number of cycles according to embodiments and comparative embodiments of the present invention is presented;

[0038] Figure 11 A cross-sectional view of a lithium metal anode according to an embodiment of the present invention; and

[0039] Figure 12 This is a cross-sectional view of the lithium metal anode according to a comparative embodiment. Detailed Implementation

[0040] Terms such as first, second, and third are used to describe (but are not limited to) various parts, components, regions, layers, and / or sections. These terms are used only to distinguish one part, component, region, layer, or section from another. Therefore, without departing from the scope of the invention, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section.

[0041] The technical terms used herein are for reference only and are not intended to limit the invention. The singular forms used herein are intended to include the plural forms unless the phrase explicitly indicates the opposite meaning. In this specification, the term "comprising" is intended to represent a particular feature, region, integral, step, operation, element, and / or component, but is not intended to exclude the presence or addition of other features, regions, integrals, steps, operations, elements, and / or components.

[0042] When it is said that a component is "above" or "on top of" another component, it can mean that it is directly above or on top of the other component, or there may be an intermediate component. Conversely, when it is said that a component is "directly" above another component, there is no intermediate component.

[0043] It should be understood that, as used herein, the terms “vehicle” or “of a vehicle” or other similar terms generally include motor vehicles, such as passenger vehicles including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, vessels including various boats and ships, aircraft, etc., and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from non-petroleum energy sources). As mentioned herein, a hybrid vehicle is a vehicle with two or more power sources, such as a vehicle that combines gasoline and electric power.

[0044] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the / said” are intended to also include the plural forms. These terms are intended only to distinguish one component from another, and the terms do not limit the nature, order, or sequence of these constitutive components. It will be further understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of the stated features, values, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, values, steps, operations, elements, components, and / or combinations thereof. As used herein, the term “and / or” includes any and all combinations of one or more of the associated enumerations. Throughout the specification, unless expressly stated to the contrary, the words “comprising” and variations such as “including” or “having” are to be understood as meaning to include the stated elements, but not excluding any other elements. Furthermore, the terms “unit,” “component,” “device,” and “module” described in this specification mean a unit for performing at least one function and operation, and may be implemented by hardware components or software components and combinations thereof.

[0045] While exemplary embodiments are described as using multiple units to perform exemplary processes, it should be understood that exemplary processes can also be performed by one or more modules. Furthermore, it should be understood that the term controller / control unit refers to a hardware device including a memory and a processor, specifically programmed to perform the processes described herein. The memory is configured to store modules, and the processor is specifically configured to execute said modules to perform one or more processes further described below.

[0046] Furthermore, the control logic of the present invention can be implemented as a non-volatile computer-readable medium on a computer-readable medium, which contains executable program instructions that are executed by a processor, controller, etc. Examples of computer-readable media include (but are not limited to) ROM, RAM, optical disc (CD)-ROM, magnetic tape, floppy disk, flash drive, smart card, and optical data storage device. The computer-readable medium can also be distributed across a network-connected computer system, thereby enabling the computer-readable medium to be stored and executed in a distributed manner via, for example, a telematics server or a controller area network (CAN).

[0047] Unless otherwise stated or obvious from the context, the term “about” as used herein is understood to mean within the normal tolerance range in the field, such as within two standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless the context clearly indicates otherwise, all numerical values ​​provided herein are modified by the term “about”.

[0048] The term "lithium metal anode" in this article refers to the negative electrode used in lithium-based electrochemical batteries.

[0049] The term "lithium metal layer" in this article refers to a layer formed on lithium metal that is configured to protect the lithium metal.

[0050] The term "polymer adhesive" in this article refers to the polymeric material within a protective layer used to hold or bond other components together.

[0051] The term "nonpolar polymeric adhesive" as used herein refers to a polymeric adhesive that is substantially free of electronegative or strongly polar functional groups. In certain aspects, a nonpolar polymeric adhesive may be at least substantially free of halogens, such as F, Br, Cl, and / or I, particularly F, and / or at least substantially free of carboxyl groups (including carbonyl, ester), amides, cyano, nitro, etc. A nonpolar polymeric adhesive may suitably be completely free of such polar groups, or the presence of such groups in the polymer may not exceed 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, or 0.5 wt% by weight of the total polymer. In some aspects, the number of repeating units containing such polar groups in the nonpolar polymeric adhesive does not exceed 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or 0.5% by weight of the total repeating units in the nonpolar polymeric adhesive.

[0052] The term "lithium conductive particles" as used in this document refers to particles included in a protective layer for facilitating the transport of lithium ions and / or electrons.

[0053] In some respects, the term “substantially free” as used herein means that the composition does not contain any intentionally added portion and that any residual or trace amounts thereof are below the threshold levels specified in this invention (e.g., less than about 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0.5 wt%, or 0.1 wt%).

[0054] The term "lithium secondary battery" as used in this article refers to a rechargeable electrochemical battery comprising a lithium metal anode, a cathode, and an electrolyte capable of transporting lithium ions, wherein the battery is designed to undergo multiple charge-discharge cycles.

[0055] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms (e.g., those defined in common dictionaries) are to be interpreted as having the meaning consistent with relevant technical literature and this invention, and not as having an idealized or overly formal meaning, unless expressly defined otherwise herein.

[0056] Figure 1 This is a schematic diagram of a lithium metal anode according to some embodiments of the present invention.

[0057] refer to Figure 1 According to some embodiments of the present invention, a lithium metal anode may include a current collector, a lithium metal layer, and a protective layer. Specifically, the lithium metal anode of the present invention includes a protective layer on a lithium metal layer, which is formed by depositing lithium batteries onto the current collector through charging and serves as a negative electrode. When applied to a battery, it can provide a lithium metal anode that blocks electrolyte permeation while allowing lithium ions to easily permeate.

[0058] The current collector is a negative electrode current collector with a lithium metal layer disposed thereon, and can be a component inside the battery used for electrical connection. The current collector is not particularly limited, as long as it is conductive and does not cause chemical changes in the lithium secondary battery. The current collector can be, in non-limiting examples, copper, stainless steel, aluminum, nickel, titanium, sintered carbon, or copper or stainless steel with a surface treated with carbon, nickel, titanium, silver, etc. Specifically, the current collector may include copper.

[0059] The current collector may be in the form of foil, but this is not a limiting example; it may also be in the form of mesh, foam, rod, wire, or sheet made of braided thread. In some embodiments, the current collector may have a structure with fine irregularities formed on its surface.

[0060] The lithium metal layer may comprise lithium metal or a lithium metal alloy. The lithium metal layer, comprising lithium metal or a lithium metal alloy, facilitates the electrodeposition of lithium during charging and discharging.

[0061] The lithium metal alloy may include lithium and an alloy of lithium with a metal or metalloid capable of alloying with lithium. The metal or metalloid capable of alloying with lithium may be, for example, a lithium-loving metal, such as aluminum, zinc, gold, silver, magnesium, bismuth, cadmium, antimony, silicon, lead, tin, gallium, germanium, or indium.

[0062] The lithium metal layer may further include a lithium-ion battery deposition layer. Specifically, the lithium metal layer may include an initial lithium layer and a lithium-ion battery deposition layer disposed on the initial lithium layer. The initial lithium layer may refer to rolled lithium disposed on the current collector to facilitate lithium-ion battery deposition, and the lithium-ion battery deposition layer may be formed as lithium moves toward the lithium metal layer during charging and discharging at the battery terminals.

[0063] In some implementations, the thickness of the lithium-ion battery deposited layer can be from 5 micrometers to 20 micrometers. Specifically, the thickness can be from 8 micrometers to 12 micrometers. When the lithium-ion battery deposited layer is formed within this thickness range, it has the advantage of enabling batteries with excellent electrochemical performance without causing the protective layer to collapse. If the thickness of the lithium-ion battery deposited layer exceeds this range, the protective layer may be damaged, leading to electrolyte leakage.

[0064] In some implementations, the average thickness ratio of the initial lithium layer to the lithium-ion battery deposited layer (initial lithium layer thickness: lithium-ion battery deposited layer thickness) can be from 5:5 to 20:20. Specifically, the average thickness ratio can be from 20:8 to 20:15.

[0065] When the average thickness ratio falls within the specified range, an anode with improved electrochemical performance can be achieved without damaging the protective layer. If the initial lithium layer thickness is too large (in terms of the average thickness ratio), the following problem arises: lithium deposition cannot be performed properly, making it impossible to improve the electrochemical performance of the anode. If the thickness of the lithium-deposited layer is too large (in terms of the average thickness ratio), the following problem arises: lithium deposition is over-performed, leading to damage to the protective layer.

[0066] The protective layer, disposed on the lithium metal layer, blocks the permeation of electrolyte while facilitating the easy penetration of lithium ions into the lithium metal layer. The protective layer may include a polymer binder and lithium conductive particles. Specifically, the protective layer may be implemented as a composite material of multiple aggregates of the polymer binder and lithium conductive particles. More specifically, the average particle size (D50) of the aggregated composite material may be from 0.4 micrometers to 0.6 micrometers.

[0067] The composite material can have a spherical shape with a sphericity of 0.6 or higher. Sphericity refers to the ratio of the minor axis length to the major axis length on the cross-section of the composite material. The composite material has a spherical shape with sphericity as described above, such that multiple composite materials are filled in the protective layer, and lithium ions migrate along the voids formed by the interfaces of the composite materials.

[0068] In some embodiments, the filling density of the polymer binder and lithium conductive particles in the protective layer can be 75% to 85%, based on 100% of the protective layer. The filling density can refer to the density of the polymer binder and lithium conductive particles filling the spaces within the protective layer. Since at least one composite material comprising polymer binder and lithium conductive particles is filled within this range, based on 100% of the protective layer, electrolyte permeation can be prevented, and lithium ion mobility can be improved.

[0069] When the filler density exceeds the upper limit of this range, lithium dendrite growth may occur due to insufficient binder distribution. If the filler density is below the lower limit of this range, capacity reduction may occur due to high resistance.

[0070] Polymer binders prevent electrolyte from penetrating into the protective layer and facilitate the aggregation of lithium conductive particles. In some embodiments, the polymer binder can be a non-polar material. Because the polymer binder is composed of a non-polar material, reactions with polar electrolytes can be minimized. If the protective layer is polar, the electrolyte may penetrate or swell in the protective layer and react with the lithium surface. Conversely, by minimizing the reaction between the polymer binder and the electrolyte, the problem of shortened battery life due to negative electrode depletion can be prevented.

[0071] In some embodiments, the polymer binder may include at least one selected from styrene-based polymers, block copolymers, polyolefin-based polymers, polyurethane-based polymers, and silica-based polymers. The silica-based polymer may be, for example, PMMA. Because the polymer binder includes the materials described above, electrolyte permeation can be prevented.

[0072] In some implementations, the polymer binder can be a highly elastic polymer. A highly elastic polymer is a polymer that is elastic enough to ensure the protective layer is not damaged even if there is uneven lithium deposition, thus easily preventing electrolyte penetration. Examples of highly elastic polymers include, for instance, (SIS) polystyrene-block-polyisoprene-block-polystyrene.

[0073] In some embodiments, the polymer binder may be fluorine-free (F). Specifically, if the polymer binder contains fluorine, the fluorine may react with lithium and inhibit lithium migration during charging and discharging, thereby reducing the electrochemical properties of the battery.

[0074] The lithium conductive particles can be particles that facilitate lithium-ion penetration. Specifically, the lithium conductive particles can help lithium ions migrate easily between the negative and positive electrodes of the battery during charging and discharging. More specifically, the lithium conductive particles can promote the easy penetration of lithium ions into the protective layer.

[0075] In some embodiments, the lithium conductive particles may, in a non-limiting example manner, include at least one of lithium-based oxides, nitrides, sulfides, fluorides, phosphides, and solid electrolyte materials. The solid electrolyte material may include at least one of LLZO, LiPON, and S-glass. Specifically, the solid electrolyte material may be LLZO (Li7La3Zr2O). 12 ).

[0076] In some embodiments, the lithium conductive particles may include a doped material. The doped material may include at least one of Nb, Ta, and Ga. Specifically, the doped material may be an Nb-based material. Because the lithium conductive particles contain a doped material, the mobility of lithium ions permeating through the electrolyte can be improved.

[0077] In some embodiments, the average particle size (D50) of the lithium conductive particles can be from 100 nm to 850 nm. The average particle size (D50) represents the particle size at which the cumulative percentage of lithium conductive particles reaches 50%. The average particle size (D50) of the lithium conductive particles can be from 400 nm to 600 nm. When the average particle size of the lithium conductive particles falls within this range, the packing density within the protective layer can be increased within a certain range, thereby facilitating the binding and movement of lithium with the polymer binder.

[0078] In some embodiments, the lithium conductive particles may include fine particles and coarse particles. Specifically, fine particles and coarse particles refer to particles with different average particle sizes (D50), and coarse particles refer to particles with a larger average particle size (D50) compared to fine particles.

[0079] In some embodiments, the weight ratio of fine particles to coarse particles in the lithium conductive particles (fine particles (wt%): coarse particles (wt%)) can satisfy 0.5:9.5 to 3.0:7.0. Specifically, this weight ratio can satisfy 0.5:9.5 to 1.5:8.5. Since the lithium conductive particles include fine and coarse particles in the above weight ratio, the packing density can be increased to promote lithium-ion migration.

[0080] If the weight ratio exceeds the upper limit of the range, the following problems arise: the particle surface area increases and the binder distribution becomes uneven, leading to lithium dendrite growth. If the weight ratio falls below the lower limit of the range, the following problems arise: the filler density decreases, resulting in slower lithium migration.

[0081] In some embodiments, the weight ratio of lithium conductive particles to polymer binder in the protective layer (lithium conductive particles (wt%) / polymer binder (wt%)) can be from 2.0 to 10.0. Specifically, the weight ratio can be from 2.3 to 9.0, more specifically from 4.0 to 6.5. When the weight ratio falls within this range, it can prevent the battery from failing to charge due to overvoltage during charging and allows lithium to be uniformly electrodeposited under the protective layer, thereby improving electrochemical characteristics.

[0082] If the weight ratio exceeds the upper limit of the range, the following problems occur: lithium batteries deposit on top of the protective film, leading to a short circuit. If the weight ratio falls below the lower limit of the range, the following problems occur: pinholes appear, causing localized lithium battery deposition, resulting in a short circuit, and early overvoltage occurs, making charging impossible.

[0083] In some implementations, the thickness of the protective layer can be from 10 micrometers to 20 micrometers. The thickness of the protective layer refers to its length in the vertical direction measured from the top surface of the lithium metal layer, and can specifically refer to the height of the protective layer. Specifically, the thickness of the protective layer can be from 12.5 micrometers to 17.5 micrometers.

[0084] When the thickness of the protective layer falls within the specified range, the battery exhibits excellent cycle life performance during charging and discharging. If the thickness of the protective layer exceeds the upper and lower limits of the specified range, the battery suffers from poor cycle life performance during charging and discharging.

[0085] In some embodiments, the protective layer may include a solvent. The solvent can be used to slurry the protective layer, thereby depositing the protective layer on the lithium metal layer. Specifically, the solvent does not react with lithium and can partially dissolve the polymer binder in the protective layer, thereby facilitating the agglomeration of the polymer binder with the lithium conductive particles.

[0086] In some embodiments, the solvent may include at least one of benzene, toluene, xylene, and alkane-based materials. Specifically, the alkane-based material may include butane, propane, pentane, etc. The solvent may be a material capable of easily mixing the polymer binder and lithium conductive particles and dissolving at least a portion of the polymer binder.

[0087] In some embodiments, the solvent may include 30% to 50% by weight of solids content, based on 100% by weight of the protective layer. Specifically, the solvent may include 35% to 45% by weight of solids content, based on 100% by weight of the protective layer. The solvent may be included in the lithium metal anode such that the solids content falls within the range described. Because the solvent content in the lithium metal anode product is within this range, the polymer binder and lithium conductive particles can be structurally stably aligned.

[0088] In some embodiments, the protective layer may further include a dispersant. The dispersant helps the polymer binder and lithium conductive particles to be easily dispersed within the protective layer. Specifically, the dispersant may be, for example, polyvinylpyrrolidone (PVP).

[0089] In some embodiments, the dispersant content may be 3% by weight or less, based on 100% by weight of the protective layer. Specifically, the dispersant content may be from 0.1% by weight to 2.0% by weight, more specifically from 0.5% by weight to 1.5% by weight, based on 100% by weight of the protective layer. When the dispersant content is within the range described, the protective layer is uniformly applied and disposed on the lithium metal layer, and the polymer binder and lithium conductive particles can be easily dispersed.

[0090] If the dispersant content exceeds the upper limit of the range, the following problem arises: the dispersant content becomes too high, while the content of polymer binder and lithium conductive particles decreases, resulting in a decline in the strength of the protective layer and the electrochemical characteristics of the negative electrode. If the dispersant content falls below the lower limit of the range, the following problem arises: the dispersant content is too low, resulting in insufficient dispersant effectiveness.

[0091] According to some embodiments of the present invention, a lithium secondary battery may include a positive electrode and a negative electrode. Specifically, a lithium secondary battery may include a positive electrode, a negative electrode located opposite the positive electrode, a separator between the positive and negative electrodes, and an electrolyte. For the negative electrode, the description of the lithium metal anode of the present invention described above can be considered without contradiction.

[0092] In addition, the lithium secondary battery may optionally further include a battery container for housing electrode assemblies for a positive electrode, a negative electrode and a separator, and a seal for sealing the battery container.

[0093] The positive electrode may include a positive current collector and a positive active material layer disposed on the positive current collector, wherein the positive active material layer may include a positive active material.

[0094] The positive electrode current collector is not particularly restricted, as long as it is conductive and does not cause chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, sintered carbon, and aluminum or stainless steel with surface treatments of carbon, nickel, titanium, silver, etc., can be used.

[0095] In some implementations, the thickness of the positive current collector can typically range from 3 micrometers to 500 micrometers, and fine irregularities may be formed on the surface of the positive current collector to enhance the adhesion of the positive active material. For example, the positive current collector can take various forms, such as films, sheets, foils, meshes, porous bodies, foams, and nonwoven fabrics.

[0096] As a positive electrode active material, compounds capable of reversibly inserting and deintercalating lithium (lithiation intercalation compounds) can be used. Specifically, one or more composite oxides of lithium with metals selected from cobalt, manganese, nickel, and combinations thereof can be used, and specific examples may include compounds represented by one of the following chemical formulas.

[0097] Li a A 1-b B b D2 (where 0.90≤a≤1.8 and 0≤b≤0.5); Li a E 1-b B b O 2-c D c (Mode

[0098] Medium, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiE 2-b B b O 4-c D c (In the formula, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b B c D α (Where, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li a Ni 1-b-c Co b B c O 2-α T α (In the formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b- c Co b B c O 2-α T2 (where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b-c Mn b B c D α (Where, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2); Li a Ni 1-b-c Mn b B c O 2-α T α(In the formula, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b-c Mn b B c O 2-α T2 (where 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni b E c G d O2 (where 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); Li a Ni b Co c Mn d GeO2 (where 0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1); Li a NiG b O2 (where 0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2 (where 0.90≤a≤1.8, 0.001≤b≤0.1); Li a MnG b O2 (where 0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4 (in the formula, 0.90≤a≤1.8, 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2PO 43 (0≤f≤2); Li (3-f) Fe2PO 43 (0≤f≤2); and LiFePO4.

[0099] In the chemical formula, A can be Ni, Co, Mn or a combination thereof; B can be Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements or a combination thereof; D can be O, F, S, P or a combination thereof; E can be Co, Mn or a combination thereof; T can be F, S, P or a combination thereof; G can be Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; Q can be Ti, Mo, Mn or a combination thereof; I can be Cr, V, Fe, Sc, Y or a combination thereof; J can be V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0100] In other embodiments, a compound having a coating layer on its surface, or a mixture of the compound and a compound having a coating layer, may be used. The coating layer may include at least one coating element compound selected from oxides, hydroxides, hydroxyoxides, carbonates, and hydroxyl carbonates of the coating element.

[0101] In some embodiments, the compound forming the coating layer can be amorphous or crystalline. For the coating elements included in the above-mentioned coating layer, Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof can be used. The coating layer formation process can employ any coating method (e.g., spraying, dipping, etc.) as long as the method can coat the compound with these elements without adversely affecting the physical properties of the positive electrode active material. Since this process is well understood by those skilled in the art, its detailed description will be omitted.

[0102] The positive electrode active material layer may further include an adhesive and / or conductive material together with the positive electrode active material. The adhesive serves to improve the adhesion between the positive electrode active material particles and the adhesion between the positive electrode active material and the positive electrode current collector. Specific embodiments include, but are not limited to: polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene diene monomer (EPDM) rubber, sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, etc., one of which may be used alone, or a mixture of two or more of them may be used. The content of the adhesive, based on the total weight of the positive electrode active material layer, may be from 1% to 30% by weight.

[0103] The conductive material is used to impart conductivity to the electrode and can be used without particular restriction, provided that it has electronic conductivity and does not cause chemical changes in the battery in which it is constructed. Specific embodiments may include, but are not limited to: graphite, such as natural graphite and artificial graphite; carbon-based materials, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal cracking black, and carbon fiber; metal powders or metal fibers, such as copper, nickel, aluminum, and silver; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; or conductive polymers, such as polystyrene derivatives, etc., which may be used alone or in mixtures of two or more. The content of the conductive material is typically from 1% to 30% by weight based on the total weight of the positive electrode active material layer.

[0104] The positive electrode can be manufactured according to existing positive electrode manufacturing methods. Specifically, the positive electrode can be manufactured as follows: a composition for forming a positive electrode active material layer is applied to a positive electrode current collector, followed by drying and rolling, wherein the composition includes a positive electrode active material and optionally, as needed, a binder, a conductive material, or a solvent. In this case, the types and contents of the positive electrode active material, binder, and conductive material are as described above.

[0105] The solvent can be any solvent commonly used in the relevant technical field, including dimethyl sulfoxide (DMSO), isopropanol, N-methylpyrrolidone (NMP), acetone, or water. One of these solvents can be used alone, or a mixture of two or more can be used. Considering the coating thickness and production yield of the slurry, the amount of solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder, while the achieved viscosity ensures excellent thickness uniformity during the manufacturing process of the positive electrode.

[0106] In other embodiments, the positive electrode can be manufactured by casting the composition for forming the positive electrode active material layer onto a separate support, and then pressing the film layer obtained by peeling it off from the support onto the positive electrode current collector.

[0107] The separator is used to separate the positive and negative electrodes and provide a migration path for lithium ions. Any separator can be used without particular limitation, as long as it is typically used as a separator in a secondary battery. In particular, separators with high electrolyte solution retention capacity and low resistance to electrolyte ion migration are preferred. Specifically, porous polymer membranes can be used, such as those made of polyolefin-based polymers (e.g., ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers, and ethylene / methacrylate copolymers), or those having a stacked structure with two or more layers. Alternatively, conventional porous nonwoven fabrics can be used, such as nonwoven fabrics made of high-melting-point glass fibers, polyethylene terephthalate fibers, etc. In other embodiments, the separator can be a coated separator comprising ceramic components or polymer materials to ensure heat resistance or mechanical strength, and can optionally be used in a single-layer or multi-layer structure.

[0108] For the electrolyte, an impregnated electrolyte used to form the aforementioned gel polymer electrolyte can be used. In addition to the electrolyte components described above, the electrolyte may further include one or more additives, such as haloalkylene carbonate compounds (e.g., difluoroethylene carbonate), pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glycol dimethyl ether, hexamethylphosphotriamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolides, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, thereby improving battery life characteristics, suppressing battery capacity degradation, and increasing battery discharge capacity, etc. In this case, the content of the additives may be from 0.1% by weight to 5% by weight, based on the total weight of the electrolyte.

[0109] Preferred embodiments and comparative embodiments of the present invention will be described below. However, the following embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to the following embodiments.

[0110] <Experimental Examples>

[0111] Preparation of lithium metal anodes

[0112] <Example 1>

[0113] <Preparation of Current Collector>

[0114] A copper foil current collector is prepared for use in the negative electrode of the lithium secondary battery of the present invention. In this example, the thickness of the copper foil current collector used is 10 micrometers.

[0115] <Formation of Lithium Metal Layer>

[0116] A lithium metal layer is formed on the current collector using a coating method on a rolling mill. In this example, a lithium metal layer with a thickness of 20 micrometers is formed.

[0117] <Formation of the protective layer>

[0118] To form a protective layer on a lithium metal layer, a protective layer slurry is prepared. The protective layer slurry is made by mixing a binder, lithium conductive particles, and a solvent. Specifically, the protective layer slurry uses a non-polar polymer SIS (polystyrene-block-polyisoprene-block-polystyrene) as a binder and NbLLZO (Li7La3Zr2O) as a solvent. 12 The lithium conductive particles are used as the lithium conductive particles, and toluene is used as the solvent. In this example, based on 100% by weight of the slurry, the composition of the protective layer slurry is: 6.3% by weight of binder, 25.3% by weight of lithium conductive particles, and 68.4% by weight of solvent, and the weight ratio of lithium conductive particles to binder in the protective layer slurry (lithium conductive particles (wt%) / binder (wt%)) is about 4.0.

[0119] For lithium conductive particles, particles with an average particle size (D50) of 500 nm and doped with 5% Nb per 100% lithium conductive particles were used.

[0120] Subsequently, a semi-automatic coating device was used to apply the protective layer slurry directly onto the lithium metal layer with a thickness of 15 micrometers using a doctor blade method.

[0121] Subsequently, the protective slurry coated on the lithium metal layer was dried in a vacuum oven at 80°C for 90 minutes.

[0122] <Comparative Example 1>

[0123] In the preparation of the lithium metal anode, the same steps as in Example 1 are performed, except that the step of coating a protective layer on the lithium metal layer is not included at all.

[0124] Control of the ratio of binder to lithium conductive particles

[0125] <Example 2>

[0126] In the preparation of the lithium metal anode, the same steps as in Example 1 were performed, except that the weight ratio of lithium conductive particles to binder in the protective layer slurry (lithium conductive particles (wt%) / binder (wt%)) was changed to approximately 9 in the protective layer formation step. Specifically, the same steps as in Example 1 were performed, except that the weight ratio of lithium conductive particles to binder (lithium conductive particles (wt%) / binder (wt%)) was 9:1.

[0127] <Example 3>

[0128] In the preparation of the lithium metal anode, the same steps as in Example 1 were performed, except that the weight ratio of lithium conductive particles to binder in the protective layer slurry (lithium conductive particles (wt%) / binder (wt%)) was changed to approximately 2.3 in the protective layer formation step. Specifically, the same steps as in Example 1 were performed, except that the weight ratio of lithium conductive particles to binder (lithium conductive particles (wt%) / binder (wt%)) was 7:3.

[0129] <Comparative Example 2>

[0130] In the preparation of the lithium metal anode, the same steps as in Example 1 were performed, except that the weight ratio of lithium conductive particles to binder in the protective layer slurry (lithium conductive particles (wt%) / binder (wt%)) was changed to approximately 1.5 in the protective layer formation step. Specifically, the same steps as in Example 1 were performed, except that the weight ratio of lithium conductive particles to binder (lithium conductive particles (wt%) / binder (wt%)) was 6:4.

[0131] Comparative Example 3

[0132] In the preparation of the lithium metal anode, the same steps as in Example 1 were performed, except that the weight ratio of lithium conductive particles to binder in the protective layer slurry (lithium conductive particles (wt%) / binder (wt%)) was changed to approximately 1 in the protective layer formation step. Specifically, the same steps as in Example 1 were performed, except that the weight ratio of lithium conductive particles to binder (lithium conductive particles (wt%) / binder (wt%)) was 5:5.

[0133] Control of protective layer thickness

[0134] <Example 4>

[0135] In the preparation of the lithium metal anode, except that the thickness of the protective layer is controlled to 20 micrometers in the protective layer formation step, the same steps as in Example 1 are performed.

[0136] <Example 5>

[0137] In the preparation of the lithium metal anode, the same steps as in Example 1 are performed, except that the thickness of the protective layer is controlled to 10 micrometers in the protective layer formation step.

[0138] <Comparative Example 4>

[0139] In the preparation of the lithium metal anode, the same steps as in Example 1 are performed, except that the thickness of the protective layer is controlled to 5 micrometers in the protective layer formation step.

[0140] Preparation of lithium secondary batteries

[0141] The positive electrode active material (LiNi) 0.9 Co 0.05 Mn 0.05 O2, conductive material (carbon nanotubes), and binder (polyvinylidene fluoride) were added to the solvent NMP in a weight ratio of 8:1:1 to prepare a positive electrode slurry. The positive electrode slurry was coated onto the surface of a 20-micrometer-thick positive electrode current collector (Al film), followed by drying and rolling to prepare the positive electrode. In this example, the loading of the positive electrode active material was 20.4 mg / cm³. 2 .

[0142] The positive electrode is arranged on an aluminum foil with a thickness of 12 micrometers. Subsequently, the positive electrode and lithium metal anode prepared according to the embodiments and comparative embodiments of the present invention are arranged face to face, a 12-micrometer polyethylene separator with a 2-micrometer alumina coating is inserted between the positive and negative electrodes, and then a non-aqueous electrolyte is injected to obtain a secondary battery.

[0143] Figure 2 and Figure 3This is a plan view of the lithium metal anode in the embodiments and comparative embodiments of the present invention.

[0144] Figure 2 This is a view to confirm whether a reaction occurs when ethanol is applied to the protective layer of the lithium metal anode prepared according to Example 1. Figure 3 The same situation as Comparative Example 1 is shown. (Reference) Figure 2 It can be confirmed that when a solution of electrolyte, such as ethanol, is applied to the protective layer, the lithium metal anode prepared according to Example 1 remains stable because ethanol does not permeate and does not react. (Reference) Figure 3 It can be confirmed that the lithium metal anode without a protective layer prepared according to Comparative Example 1 exhibits high reactivity with the polar solution, thereby reacting with polar substances forming the electrolyte, such as ethanol, leading to oxidation. Therefore, it can be confirmed that without a protective layer, the following problem exists: lithium metal reacts with the electrolyte, resulting in a shortened negative electrode lifespan.

[0145] Figure 4 and Figure 5 This is a cross-sectional view of a lithium metal anode according to embodiments and comparative embodiments of the present invention.

[0146] Figure 4 and Figure 5 Results of lithium electrodeposition cross-sections of the lithium metal anodes according to Example 1 and Comparative Example 1 are shown respectively. In Example 1, where the lithium metal anode is coated with a protective layer, it was confirmed that the lithium electrodeposition thickness was approximately 10 micrometers when electrodeposited onto existing lithium with a thickness of 20 micrometers. In Comparative Example 1, it was confirmed that the lithium electrodeposition thickness was approximately 18 micrometers when electrodeposited onto existing lithium with a thickness of 20 micrometers.

[0147] Figure 6 and Figure 7 A graph illustrating the lifetime characteristics of lithium metal anodes according to embodiments and comparative embodiments of the present invention is provided.

[0148] Figure 6 and Figure 7 The lifetime characteristics of lithium metal anodes according to Example 1 and Comparative Example 1 are shown. It can be confirmed that the cycle life of Example 1 is about 152 cycles, while the cycle life of Comparative Example 1 is about 133 cycles, indicating that the lithium metal anode including the protective layer has superior lifetime characteristics.

[0149] Figure 8 A graph showing the charging voltage vs. capacity according to embodiments and comparative embodiments of the present invention is shown.

[0150] Figure 9 This is a plan view of the surface of a lithium metal anode after full charging, according to embodiments and comparative embodiments of the present invention.

[0151] Figure 8 A graph showing the single full charge voltage of lithium metal anodes prepared according to Comparative Example 1 (bare), Comparative Example 2 (NbLLZO5), Comparative Example 3 (NbLLZO6), Example 1 (NbLLZO8), Example 2 (NbLLZO9), and Example 3 (NbLLZO7) of the present invention is provided. Specifically, to obtain the full charge voltage curve, the voltage was cut off to 4.25V at a constant current charging rate of C / 10, and the charging voltage versus capacity is plotted in the graph. Figure 9 The image shows a plan view of the lithium anode surface after full charging. From left to right, these are Comparative Example 1, Comparative Example 3, Comparative Example 2, Example 3, Example 1, and Example 2.

[0152] By viewing Figure 8 and Figure 9 It can be confirmed that in Comparative Example 1, where no protective layer was formed, a reference charging voltage curve was observed. However, in Example 1, which included a protective layer, the overpotential increased compared to Comparative Example 1, but full charging was successful, and the lithium battery was deposited under the protective film. Furthermore, comparing Examples 1 to 3 with Comparative Examples 2 and 4, it can be confirmed that Examples 1 to 3 have superior charging voltage values ​​compared to Comparative Examples 2 and 4.

[0153] It can be confirmed that in Comparative Example 2, charging was impossible due to early overvoltage and short circuit, and lithium was partially electrodeposited through the pinhole, causing a short circuit. It can also be confirmed that in Comparative Example 3, charging was impossible due to early overvoltage and short circuit, and lithium was partially electrodeposited through the pinhole, causing a short circuit.

[0154] Figure 10 A graph showing capacity vs. number of cycles according to embodiments and comparative embodiments of the present invention is presented.

[0155] For Comparative Example 1 (naked), Comparative Example 4 (5 micrometers), Example 1 (15 micrometers), Example 4 (20 micrometers), and Example 5 (10 micrometers), the following methods were used to measure... Figure 10 The cyclic experimental conditions.

[0156] For the formation conditions, proceed in sequence: i) cut off the voltage to 4.25V at a constant current charging rate of C / 10, ii) wait 10 minutes, iii) cut off the voltage to 3.0V at a constant current charging rate of C / 10, iv) wait 10 minutes. For the C / 3-C / 3 cycle conditions, i) maintain the voltage at 4.25V and charge at a constant current charging rate of C / 3 until the current cutoff of C / 20, ii) wait 10 minutes, iii) cut off the voltage to 3.0V at a constant current discharging rate of C / 3, iv) wait 10 minutes, v) repeat i) to iv).

[0157] refer to Figure 10 It was confirmed that Comparative Example 1 had approximately 240 cycles, Comparative Example 4 had approximately 160 cycles, Example 1 had approximately 268 cycles, Example 4 had approximately 264 cycles, and Example 5 had approximately 186 cycles. Therefore, it was confirmed that when the protective film thickness is too small, the following problem exists: shortened cycle life, leading to premature short circuits. Furthermore, by examining Examples 1, 4, and 5, it was confirmed that when the optimal thickness of the protective film is in the range of approximately 15 to 20 micrometers, the cycle life is significantly superior.

[0158] Figure 11 and Figure 12 This is a cross-sectional view of a lithium metal anode according to embodiments and comparative embodiments of the present invention.

[0159] Figure 11 and Figure 12 Cross-sections of the lithium metal anodes according to Example 1 and Comparative Example 4 after full charging are shown respectively. In Example 1, it was confirmed that after full charging, the current collector, rolled lithium, electrodeposited lithium, and protective film were sequentially disposed in the lithium metal anode. However, in Comparative Example 4, it was confirmed that after full charging, the current collector, rolled lithium, protective film, and electrodeposited lithium were sequentially disposed in the lithium metal anode, indicating a problem of lithium electrodeposition on top of the protective film. Therefore, it can be confirmed that lithium-stable electrodeposition of lithium metal anodes can only be prepared when the thickness of the protective film is 10 micrometers or greater, particularly 15 micrometers or greater.

[0160] Those skilled in the art will understand that this invention is not limited to the embodiments described above, but can be made in various different forms and can be implemented in other specific forms without altering the technical spirit or essential characteristics of the invention. Therefore, the above embodiments should be understood as illustrative in all respects and not for limiting purposes.

Claims

1. A lithium metal anode, comprising: A lithium metal layer disposed on the current collector; as well as A protective layer disposed on the lithium metal layer The protective layer comprises a polymer adhesive and lithium conductive particles. The polymer adhesive is non-polar.

2. The lithium metal anode according to claim 1, wherein: The weight ratio of the lithium conductive particles to the polymer binder, i.e., the weight % of the lithium conductive particles / the weight % of the polymer binder, is 2.0 to 10.

0.

3. The lithium metal anode according to claim 1, wherein: The thickness of the protective layer is 10 micrometers to 20 micrometers.

4. The lithium metal anode according to claim 1, wherein: The average particle size of the lithium conductive particles is 100 nanometers to 850 nanometers.

5. The lithium metal anode according to claim 1, wherein: The polymer adhesive is a polystyrene-block-polyisoprene-block-polystyrene.

6. The lithium metal anode according to claim 1, wherein: The polymer adhesive is fluorine-free.

7. The lithium metal anode according to claim 1, wherein: The polymer adhesive includes at least one of styrene-based polymers, block copolymers, polyolefin-based polymers, polyurethane-based polymers, and silica-based polymers.

8. The lithium metal anode according to claim 1, wherein: The lithium conductive particles include at least one of lithium-based oxides, nitrides, sulfides, fluorides, phosphides, and solid electrolyte materials.

9. The lithium metal anode according to claim 1, wherein: The protective layer includes a solvent. The solvent contains 30% to 50% solids per 100% by weight of the protective layer.

10. The lithium metal anode according to claim 9, wherein: The solvent includes at least one of benzene, toluene, xylene, and alkane-based materials.

11. The lithium metal anode according to claim 1, wherein: The protective layer further includes a dispersant. The content of the dispersant is 3% by weight or less, based on 100% by weight of the protective layer.

12. The lithium metal anode according to claim 1, wherein: The lithium conductive particles include doped materials. The doped material is an Nb-based material.

13. The lithium metal anode according to claim 1, wherein: Based on 100% of the protective layer, the fill density of the polymer adhesive and the lithium conductive particles in the protective layer is 75% to 85%.

14. The lithium metal anode according to claim 1, wherein: The lithium conductive particles include fine particles and coarse particles with an average particle size larger than the fine particles. The weight ratio of the fine particles to the coarse particles, i.e., the weight percentage of fine particles to the weight percentage of coarse particles, is between 0.5:9.5 and 3.0:7.

0.

15. The lithium metal anode according to claim 1, further comprising: The lithium battery deposition layer in the lithium metal layer, wherein, The thickness of the lithium battery deposition layer is 5 micrometers to 15 micrometers.

16. The lithium metal anode according to claim 1, wherein: The lithium metal layer further includes an initial lithium layer and a lithium battery deposition layer disposed on the initial lithium layer. The average thickness ratio of the initial lithium layer to the lithium battery deposited layer, i.e., the initial lithium layer: lithium battery deposited layer, is 5:5 to 20:

20.

17. A lithium secondary battery comprising the lithium metal anode according to claim 1.

18. A lithium metal anode, comprising: A lithium metal layer disposed on the current collector; as well as A protective layer disposed on the lithium metal layer The protective layer comprises a polymer adhesive and lithium conductive particles. The polymer adhesive is non-polar and fluorine-free, and The thickness of the lithium battery deposition layer in the lithium metal layer is 15 micrometers or greater.

19. A lithium metal anode, comprising: A lithium metal layer disposed on the current collector; as well as A protective layer disposed on the lithium metal layer The protective layer comprises a polymer binder and lithium conductive particles. The polymer adhesive is non-polar and fluorine-free, and The weight ratio of lithium conductive particles to polymer binder, i.e., weight % of lithium conductive particles / weight % of polymer binder, is 2.0 to 10.

0.

20. The lithium metal anode according to claim 19, wherein, The lithium conductive particles are NbLLZO8, and the polymer binder is polystyrene-block-polyisoprene-block-polystyrene.

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